Speaker shutoff



O. CL WELLS SPEAKER SHUTOFF Dec. 16, 1969 Filed March 2l, 1967 INVENTOR.ORVILLE C. WELLS Ibi 5% @WIIHIIIIIIM` TTQNEWS United States Patent O3,484,552 SPEAKER SHUTOFF Orville C. Wells, Kansas City, Kans., assignorto Drive- In Theater Manufacturing Company, Inc., Kansas City, Kans., acorporation of Missouri Filed Mar. 21, 1967, Ser. No. 624,821 Int. Cl.H01h 3/16 U.S. Cl. 179--1 5 Claims ABSTRACT OF THE DISCLOSURE A speakerunit containing a loud speaker has a supporting arm projecting therefromand adapted to selectively mount the speaker unit on an automobile or astationary post through which electrical wires extend to the loudspeaker. Conductive, integral Contact members are provided on thespeaker unit and the post in relative positions whereby when the speakerunit is mounted on the post the contact members engage, shorting out theelectrical signal to the loud speaker and thereby silencing the speakerwithout the use of switches having moving parts.

In multiple loud speaker systems such as those used in conventionaldriveein theaters, individual loud speaker units are temporarily mountedin or on customers automobiles. A typical speaker unit for this purposehas a loud speaker mounted in a housing including a projectingsupporting arm adapted to be hooked over a car door or window, thehousing carrying a volume control. When the speaker units are not inuse, they are stored on suitable supporting arm receiving posts providedadjacent each parking space. However, customers frequently neglect toshut the speaker olf upon leaving the theater and the sounds may bedisturbing to other customers or those living in the vicinity of thetheater. Thus, theater employees must continually check and shut offspeaker units during and after performances.

It has heretofore been suggested to provide shutoif switches on thespeaker units which are actuated when the unit is mounted on the post.Such switches, however, have often been proven to be unsatisfactorybecause of the substantial expense involved in the purchase andinstallation thereof and their inability to withstand the extremelyrough usage to which they are often subjected.

The Shuto for speaker units disclosed herein requires no -moving parts,but, rather comprises contact areas which short circuit or bypass thesignal to the loud speaker when the speaker unit rests on the post. `Itis the principal objects of the present invention to provide a speakershuto arrangement which is operable without moving parts; to providesuch a shutoff which is simple in both circuit construction and physicalconstruction; and to provide such an arrangement which is inexpensive,substantially foolproof and well adapted for its intended purposes.

Other objects and advantages of this invention will become apparent fromthe following description taken in connection with the accompanyingdrawings wherein are set forth by way of illustration and examplecertain embodiments of this invention.

FIG. l is a fragmentary perspective view showing a post adapted to mounta pair of speaker units thereon when not in operation, the speaker unitsbeing electrically connected to the post through flexible electricalcords.

FIG. 2 is a vertical cross sectional view through a speaker unit on anenlarged scale particularly showing a loud speaker therein andelectrical circuit components associated therewith.

FIG. 3 is a vertical cross sectional view on an enlarged scale throughthe upper portion of the post particularly showing components containedwithin a junction box associated with the post.

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FIG. 4 is a schematic electrical circuit diagram showing therelationship between the post assembly and speaker units.

Referring to the drawings in more detail:

The reference numeral 1 generally indicates speaker units embodying thisinvention and adapted for use in a drive-in theater system. Each speakerunit 1 comprises a movable electrically conductive housing 2 having aloud speaker 3 mounted therein for directing sound through suitablelouvers 4. A flexible electrical conductor cord 5 is directed into thehousing 2 and carries a pair of electrical leads 6 and 7 which arerespectively connected to opposite ends 8 and 9 of a resistor 10. Theresistor 10` is of the type having a movable tap connected to a terminal11 whereby moving the tap produces a varying potential between the end 8and terminal 11.

The end 8 of the resistor 10 is connected through a lead 12 to aterminal 13 which is connected to one end or side of the loud speakervoice coil 14. The terminal 11 is connected through a suitable xedresistor 15 to a terminal 16 which is grounded with respect to thehousing 2, the housing being entirely or partially of a conductivemetal. The grounded terminal 16 is also connected to a terminal 17 whichis common with the other end or side of the voice coil 14.

The housing 2 has a supporting arm 18 projecting therefrom andterminating in a downwardly hooked portion 19 whereby the supporting armis adapted, for example, to engage the window or window ledge of anautomobile for retaining the housing in the automobile so that theoccupants can easily hear the sound emanating from the loud speaker 3.The rear 20 of the housing 2 has an electrically conductive, lowresistance, contact member or area 21 beneath the supporting arm 18 fora purpose described hereinafter.

A rigid stationary post 22 projects upwardly from a position adjacentthe automobile parking space and electrical conductors 23 extendupwardly therethrough from a central signal generating system (notsho-wn) adapted to simultaneously provide speaker actuating signals fora large number of speaker units. The post 22 has a junction box 24mounted on the upper portion thereof with a suitable retaining ordepressed section 25 adapted to receive the hook portion 19 forretaining the speaker units when not in use. The junction box 24 haslaterally exposed walls 26 of electrically conductive material, such ascommon metal, and an exposed electrically conductive, low resistancecontact member or area 27 thereon which is positioned to contact thearea 21 on the speaker unit when the unit is retained on the junctionbox as shown at 28. A suitable drain hole 29, or the like, may beprovided through a wall of the junction box 24 to drain the depressedsection 25.

The junction box 24 contains a transformer 30 having an input section 31receiving electrical signals from. the conductors 23, and an outputsection 32. The output section 32 is connected through leads 33 and 34to the respective leads 7 and 6 of the speaker units for directing theoutput signal across the resistor 10. The lead 33 is grounded at 35 tothe walls 26 of the junction box 24 through a lead 36 connected to amounting screw 37 of a terminal strip 38 contained within the junctionbox.

In operation, when the speaker unit is mounted on or in an automobile,the signal from the central system conductors 23 are fed into thetransformer 30 where they are suitably modified and directed across theresistor 10 within the speaker units 1. The occupant of the car, byturning a control knob (not shown) which moves the tap of the resistor10, causes the desired strength of signal to pass through the voice coil14 of the loud speaker 3 to produce an appropriate sound volume. At theconclusion of the entertainment, the automobile occupant replaces thespeaker unit on the post by hooking the supporting arm 1S in thedepressed section 25 of the junction box 24. In doing so, the contactareas 21 and 27, respectively on the speaker unit and junction box, comeinto contact, completing an electrical pathway therebetween. When thisoccurs, current iiows through the current limiting resistor 15 directlyto the transformer output lead 33, thus bypassing the voice coil 14 andthereby eliminating any sound emanating from the loud speaker 3 althoughthe volume position of the resistor remains in a sound producingposition. The current limiting resistor restricts current tiow throughthe shorted circuit to a reasonable rate.

With the arrangement above described, sound production is automaticallyeliminated upon hanging the speaker unit on the post, without the needfor complex switches or other devices having moving parts.

It is to be understood that while one form of this invention has beenillustrated and described, it is not to be limited thereto exceptinsofar as such limitations are included in the following claims.

What is claimed and desired to be secured by Letters Patent is:

1. In a drive-in system:

(a) a speaker unit having a housing, a loud speaker mounted in saidhousing, said housing having supporting means associated therewith andadapted to engage an automobile for selectively retaining said housingthereon,

(b) a rest member adapted to receive and retain said housing when not onsaid automobile, signal means having an electrical signal output sectionassociated with said rest member,

(c) said loud speaker having a voice coil therein one side of said voicecoil being electrically connected through an elongated tlexible line toone side of said output section, a current limiting resistor in saidhousing and having one side thereof electrically connected to the otherside of said voice coil and the other side thereof electricallyconnected through an elongated flexible line to the other side of saidsignal output section,

0 member,

(e) whereby electrical signals from said output section are shuntedaround said voice coil, thereby preventing actuation of said loudspeaker during non-use of said speaker unit.

2. The apparatus as set forth in claim 1 wherein:

(a) said housing is of electrically conductive material and said secondcontact member is an exposed area of said housing.

3. The apparatus as set forth in claim 1 wherein:

(a) said rest member includes a junction box having electricallyconductive walls and said first contact member is an exposed area on oneof said walls. 4. The apparatus as set forth in claim 1 including:

side of said current limiting resistor. 5. The apparatus as set forth inclaim 1 including:

(a) a plurality of said speaker units respectively connected in parallelrelation to said signal output section.

References Cited UNITED STATES PATENTS 3 2,688,657 9/1954 wilson.

2,753,410 7'/ 1956 Melkon.

KATHLEEN H. CLAFFY, Primary Examiner J. S. BLACK, Assistant ExaminerU.S. Cl. X.R. 200-6158 (a) a volume resistor in said housing andconnected between the sides of said output section, said volume resistorhaving a movable tap connected to said other

